//-----------------------------------------------------------------------------
// MurmurHash3 was written by Austin Appleby, and is placed in the public
// domain. The author hereby disclaims copyright to this source code.

/* We only get the MurmurHash3_x64_128() here, and rename it as wuy_murmurhash(). */

#include <stdint.h>

#include "wuy_murmurhash.h"

static uint64_t rotl64 ( uint64_t x, int8_t r )
{
	return (x << r) | (x >> (64 - r));
}

static uint64_t fmix64 ( uint64_t k )
{
	k ^= k >> 33;
	k *= 0xff51afd7ed558ccdLLU;
	k ^= k >> 33;
	k *= 0xc4ceb9fe1a85ec53LLU;
	k ^= k >> 33;

	return k;
}

void wuy_murmurhash(const void *key, int len, void *out)
{
	const uint8_t * data = (const uint8_t *)key;
	const int nblocks = len / 16;

	uint64_t h1 = 0xae27729cb202352bLLU;
	uint64_t h2 = 0xd5e7551b9199b903LLU;

	const uint64_t c1 = 0x87c37b91114253d5LLU;
	const uint64_t c2 = 0x4cf5ad432745937fLLU;

	// body
	const uint64_t * blocks = (const uint64_t *)(data);

	int i;
	for (i = 0; i < nblocks; i++)
	{
		uint64_t k1 = blocks[i*2+0];
		uint64_t k2 = blocks[i*2+1];

		k1 *= c1; k1  = rotl64(k1,31); k1 *= c2; h1 ^= k1;

		h1 = rotl64(h1,27); h1 += h2; h1 = h1*5+0x52dce729;

		k2 *= c2; k2  = rotl64(k2,33); k2 *= c1; h2 ^= k2;

		h2 = rotl64(h2,31); h2 += h1; h2 = h2*5+0x38495ab5;
	}

	// tail
	const uint8_t * tail = (const uint8_t*)(data + nblocks*16);

	uint64_t k1 = 0;
	uint64_t k2 = 0;

	switch(len & 15) {
	case 15: k2 ^= ((uint64_t)tail[14]) << 48;
	case 14: k2 ^= ((uint64_t)tail[13]) << 40;
	case 13: k2 ^= ((uint64_t)tail[12]) << 32;
	case 12: k2 ^= ((uint64_t)tail[11]) << 24;
	case 11: k2 ^= ((uint64_t)tail[10]) << 16;
	case 10: k2 ^= ((uint64_t)tail[ 9]) << 8;
	case  9: k2 ^= ((uint64_t)tail[ 8]) << 0;
		 k2 *= c2; k2  = rotl64(k2,33); k2 *= c1; h2 ^= k2;

	case  8: k1 ^= ((uint64_t)tail[ 7]) << 56;
	case  7: k1 ^= ((uint64_t)tail[ 6]) << 48;
	case  6: k1 ^= ((uint64_t)tail[ 5]) << 40;
	case  5: k1 ^= ((uint64_t)tail[ 4]) << 32;
	case  4: k1 ^= ((uint64_t)tail[ 3]) << 24;
	case  3: k1 ^= ((uint64_t)tail[ 2]) << 16;
	case  2: k1 ^= ((uint64_t)tail[ 1]) << 8;
	case  1: k1 ^= ((uint64_t)tail[ 0]) << 0;
		 k1 *= c1; k1  = rotl64(k1,31); k1 *= c2; h1 ^= k1;
	};

	// finalization
	h1 ^= len; h2 ^= len;

	h1 += h2;
	h2 += h1;

	h1 = fmix64(h1);
	h2 = fmix64(h2);

	h1 += h2;
	h2 += h1;

	((uint64_t*)out)[0] = h1;
	((uint64_t*)out)[1] = h2;
}

